The calcium-sensing receptor and vitamin D receptor expression in tertiary hyperparathyroidism

• Published in: International journal of molecular medicine 2006-05, Vol.17 (5), p.779-783
• Main Authors: Grzela, Tomasz, Chudzinski, Witold, Lasiecka, Zofia, Niderla, Justyna, Wilczynski, Grzegorz, Gornicka, Barbara, Wasiutynski, Aleksander, Durlik, Magdalena, Boszczyk, Anna, Brawura-Biskupski-Samaha, Robert, Dziunycz, Piotr, Milewski, Lukasz, Lazarczyk, Marta, Lazarczyk, Maciej, Nawrot, Ireneusz
• Format: Article
• Language: English
• Subjects: Adult; Blotting, Western; Female; Humans; Hyperparathyroidism - metabolism; Hyperparathyroidism - pathology; Immunohistochemistry; Male; Middle Aged; Parathyroid Glands - chemistry; Parathyroid Glands - pathology; Receptors, Calcitriol - analysis; Receptors, Calcitriol - biosynthesis; Receptors, Calcium-Sensing - analysis; Receptors, Calcium-Sensing - biosynthesis
• ISSN: 1107-3756; 1791-244X
• DOI: 10.3892/ijmm.17.5.779

The parathormone (PTH) production is controlled by calcium and vitamin D, which interact with the calcium-sensing receptor (CaSR) and vitamin D receptor (VDR), respectively. All of these elements control calcium homeostasis, which is crucial for many physiological processes. Thus, impairment of the upstream component of this system, e.g. a decrease of CaSR and/or VDR, could result in hyperparathyroidism (HPTH). Therefore, the aim of this study was to assess the expression of CaSR and VDR in a tertiary form of HPTH (T-HPTH). The study involved 19 T-HPTH patients qualified for parathyroidectomy and 21 control parathyroids harvested from multi-organ cadaver donors. The small fragments of harvested glands were homogenized and used for Western blot analysis, whereas the remaining tissues underwent routine hematoxylin-eosin staining or immunostaining for CaSR and VDR. Among 64 T-HPTH parathyroids, 58 revealed the morphology of benign hyperplasia, 2 were identified as adenoma and 4 were classified as normal; some glands displayed a mixed histological phenotype. Western blot analysis revealed a decrease of CaSR and VDR in hyperplasia and adenoma-derived samples. However, no correlation between the types of hyperplasia and receptor expression was observed. On the other hand, microscopic analysis of CaSR- and VDR-immunostained sections revealed a highly differentiated and significantly decreased mean expression of both receptors, which correlated with parathyroid histology. The reason behind the impaired expression of CaSR and VDR in T-HPTH is unclear. It presumably results from constant parathyroid stimulation at the stage of S-HPTH, followed by further development of polyclonal autonomy. However, the verification of this thesis requires further study.